Apparatus for heating lubricating oil

ABSTRACT

An apparatus is described for heating oil for an internal-combustion engine. The apparatus includes a heat-exchanger arranged within an oil sump of the internal-combustion engine, which is flowed through or capable of being flowed through by a thermal medium for the purpose of emitting heat to oil in the oil sump. The apparatus further includes a heat-source in fluidic communication with the heat-exchanger, which is designed to heat the thermal medium outside the oil sump and outside the internal-combustion engine.

BACKGROUND 1. Technical Field

The present disclosure relates to an apparatus for heating lubricating oil for an internal-combustion engine.

2. Related Art

At low ambient temperatures the higher viscosity of a lubricating oil that is being employed for lubricating the internal-combustion engine impairs the startability thereof. In addition, a cold start places a burden on the internal-combustion engine as a result of a rapid and uneven heating of individual components. Fuel consumption and pollutant emissions may also be elevated by the higher viscosity of the lubricating oil during a cold-start phase. In addition, a low power output (for instance, when idling) and a large volume of oil (for instance, in the case of utility vehicles) can lengthen the cold-start phase.

SUMMARY

Consequently the object of the present disclosure is to make available a technical procedure that ensures the cold startability of an internal-combustion engine within a certain ambient-temperature range and shortens a cold-start phase.

According to one aspect of the disclosure, an apparatus is made available for heating lubricating oil for an internal-combustion engine. The apparatus includes a heat-exchanger arranged within an oil sump of the internal-combustion engine, which is flowed through or capable of being flowed through by a thermal medium for the purpose of emitting heat to lubricating oil in the oil sump, and a heat-source in fluidic communication with the heat-exchanger, which is designed to heat the thermal medium outside the oil sump and outside the internal-combustion engine.

The internal-combustion engine may include a combustion engine and/or a transmission. The lubricating oil may comprise engine oil and/or transmission oil. The oil sump may be arranged beneath an engine block of the combustion engine and/or beneath the transmission.

The apparatus may further include at least one sensor for registering at least one temperature. The apparatus may include a sensor for registering an actual temperature of the lubricating oil in the oil sump, a sensor for registering a forward-feed temperature in a forward feed of the heat-exchanger, and/or a sensor for registering the return-feed temperature in a return feed of the heat-exchanger.

The apparatus may further include a regulation system which is designed to regulate a power output of the heat-source in a manner depending on the at least one registered temperature. The power output of the heat-source can be regulated in such a way that the registered forward-feed temperature and/or the registered return-feed temperature of the heat-exchanger is/are higher than the actual temperature of the lubricating oil in the oil sump. The regulation system may be designed to bring about the heating of the lubricating oil by virtue of a return-feed temperature and/or a forward-feed temperature that is/are higher than the actual temperature.

The apparatus may further include a reservoir of the thermal medium, arranged outside the oil sump. The heat-exchanger and the reservoir may be in fluidic communication in a circuit of the thermal medium. The return-feed temperature can be registered between the heat-exchanger and the reservoir of the thermal medium.

The regulation system may further be designed to decrease or to limit the power output of the heat-source if the return-feed temperature is higher than a predetermined maximal temperature of the reservoir.

A suction point of a lubricating-oil circuit spatially assigned to the heat-exchanger may be arranged in the oil sump. For instance, the suction point may be arranged at the bottom of the oil sump beneath the heat-exchanger.

The heat-exchanger may comprise a plurality of plates arranged in parallel. The plates may be heat-conducting (for example, made of copper). The plates each exhibit a cavity into which the thermal medium flows. Alternatively or in supplement, the suction point may be arranged between the plates.

The plates may be spaced from one another. The plates may form interspaces. Each of the plates may be arranged in the oil sump below a desired level of the lubricating oil. The lubricating oil is able to flow in the interspaces. At least some of the oil-conducting interspaces may lead into the oil sump in such a way that the lubricating oil flows out of the oil sump directly into the oil-conducting interspaces. The interspaces can be flowed through and/or filled up by the lubricating oil. The plates may be wetted on both sides by the lubricating oil.

The heat-exchanger may include at least two connecting pipes. The thermal medium is able to flow in each of the connecting pipes. At a first connecting pipe the thermal medium can be supplied to the heat-exchanger (forward feed). At a second connecting pipe the thermal medium can be drawn off from the heat-exchanger (return feed). The connecting pipes of the forward feed and of the return feed can furthermore fasten the heat-exchanger mechanically within the oil sump.

The oil sump may include a peripheral connecting flange. The plates may be arranged parallel to a plane of the connecting flange. The heat-exchanger may include connecting pipes which are arranged within an opening, surrounded by the connecting flange, in the oil sump. The connecting pipes and/or the heat-exchanger may be arranged without direct contact with the oil sump. The heat-exchanger may be suspended in the oil sump.

Alternatively or in supplement, the oil sump may include a peripheral connecting flange, and the plates may be arranged perpendicular to a plane of the connecting flange. The heat-exchanger may include connecting pipes which lead through a side wall of the oil sump. The heat-exchanger may be fastened laterally in the oil sump. The connecting pipes may be fastened, for example screwed, to the side wall.

Furthermore, the plates of the heat-exchanger, which are parallel to one another, may be arranged at an angle relative to the plane of the connecting flange. The angle may amount to between 0° and 90°. The angle may be determined by the side wall. The side wall may be inclined relative to an opposite wall of the oil sump by the angle (or by an angle complementary to 90°). The plates of the heat-exchanger may be parallel to the side wall. For instance, the angle may be greater than or equal to 30°, and/or the angle may be less than or equal to 60°.

The suction point may be in alignment with the plates (or with some of the plates). The suction point may be arranged with respect to the heat-exchanger in such a way that a projection of the interspaces (or of one of the interspaces) parallel to the plates covers the suction point.

The thermal medium may comprise cooling water of the internal-combustion engine. The thermal medium may have been diverted from a cooling-water circuit of the internal-combustion engine. The forward feed and/or return feed of the thermal medium may form a lateral branch relative to the cooling-water circuit of the internal-combustion engine. The internal-combustion engine can act as a reservoir.

BRIEF DESCRIPTION OF THE FIGURES

Features described above and below can be realized in any combination. Further features and advantages of the disclosure will be described in the following with reference to the appended drawings.

Shown are:

FIG. 1 schematically, a perpendicular cross section of a first embodiment of an apparatus for heating engine oil or transmission oil;

FIG. 2 schematically, a perpendicular cross section of a second embodiment of an apparatus for heating engine oil or transmission oil;

FIG. 3 a schematic block diagram of a third embodiment which can be combined with either of the apparatuses presented in FIGS. 1 and 2;

FIG. 4 a schematic block diagram of a fourth embodiment which can be combined with either of the apparatuses presented in FIGS. 1 and 2;

FIG. 5 a first isometric illustration of a further development of the embodiment presented in FIG. 2;

FIG. 6 a second isometric illustration of the further development presented in FIG. 5;

FIG. 7 schematically, a perpendicular cross section of an exemplary first heat-exchanger arrangement which can be combined with the embodiments; and

FIG. 8 schematically, a perpendicular cross section of an exemplary second heat-exchanger arrangement which can be combined with the embodiments.

DETAILED DESCRIPTION

FIG. 1 shows an apparatus, labelled generally by reference symbol 100, for heating lubricating oil for an internal-combustion engine. FIG. 1 shows a perpendicular cross section of a first embodiment of the apparatus 100.

The apparatus 100 includes a heat-exchanger 104, arranged within an oil sump 102 of the internal-combustion engine, and a heat-source 106 in fluidic communication with the heat-exchanger 104. The heat-source 106 is arranged outside the oil sump 102. Irrespective of an operating temperature of the internal-combustion engine, the heat-source 106 emits heat to the thermal medium. Said thermal medium flows through the heat-exchanger 104 for the purpose of emitting heat to lubricating oil 108 in the oil sump 102.

A suction point 110 of an oil circuit is spatially assigned to, preferentially arranged beneath, the heat-exchanger 104. The heat-exchanger 104 is arranged completely below a desired level 112 of the lubricating oil 108 in the oil sump 102.

The apparatus 100 further includes a regulation system 120 for controlling a thermal power of the heat-source 106. The regulation system 120 is temperature-dependent and optionally time-controlled. The regulation system 120 is designed to ensure a startability of the internal-combustion engine within a predetermined ambient-temperature range, for instance at and/or above an ambient temperature of −46° C. To this end, the regulation system 120 controls the heat-source 106 for the purpose of heating the thermal medium of the heat-exchanger 104 until a minimum temperature of the lubricating oil 108 has been attained.

Optionally, the regulation system 120 registers an actual level of the lubricating oil 108, for instance by means of a float or by means of radar beams reflected from a surface of the lubricating oil 108. If the actual level is lower than the desired level, an output of thermal power from the heat-source 106 does not happen.

By virtue of the heat emitted by the heat-exchanger 104 to the lubricating oil 108, the temperature of the lubricating oil 108 is increased and the viscosity of the lubricating oil 108 is decreased. As a result, the internal-combustion engine can be started also at low ambient temperatures.

The heat-exchanger 104 comprises a plurality of parallel plates 114 which are each flowed through by the thermal medium. The thermal plates 114 are spaced from one another. Interspaces between adjacent thermal plates 114 are flowed around by the lubricating oil 108 for an effective transfer of heat from the thermal plates 114 to the lubricating oil 108.

By virtue of the thermal plates 114, a compact style of construction of the heat-exchanger 104 within the oil sump 102 is made possible. For instance, the surface area for the transfer of heat is enlarged by the plurality of thermal plates 114.

The thermal plates 114 have been manufactured from a material having high thermal conductivity, for instance having a thermal conductance (for example, at the minimum temperature of the lubricating oil 108 or at 20° C.) of at least 400 W/(m·K). By virtue of the high thermal conductivity of the thermal plates 114, the thickness thereof can be reduced, so that the volume of oil displaced by the heat-exchanger 104 is decreased without diminution of the effective surface area for the transfer of heat.

Optionally, the heat-exchanger 104 is employed within a high temperature range of the lubricating oil 108 for the purpose of cooling the lubricating oil 108. As a result, within differing temperature ranges of the lubricating oil 108 both functions, for heating and for cooling the lubricating oil 108, can be realized by means of the heat-exchanger 104 in the oil sump 102, without an additional heat-exchanger.

Whereas the first embodiment of the apparatus 100 shown in the perpendicular cross section of the oil sump 102 in FIG. 1 exhibits horizontally arranged thermal plates 114 which are positioned in the oil sump 102 via the connecting pipes 116 and 118 for the entry and exit, respectively, of the thermal medium, in the second embodiment of the apparatus 100 shown in FIG. 2 the heat-exchanger 104 is fastened to a side wall of the oil sump 102 via the connecting pipes 116 and 118. For instance, the connecting pipes 116 and 118 are screwed to the oil sump 102. The thermal plates 114 of the heat-exchanger 104 in the second embodiment shown in FIG. 2 are parallel to the perpendicular cross section of the image plane of FIG. 2.

Besides the function of the heating of the lubricating oil for a cold start, any embodiment of the apparatus 100 may furthermore be employed for the purpose of controlling the temperature of the lubricating oil 108 during the operation of the internal-combustion engine at low ambient temperatures.

The lubricating oil can be employed for the purpose of lubricating a combustion engine and/or a transmission connected to said engine by the oil circuit.

The external heat-source 106 may be battery-operated. Alternatively, the external heat-source 106 comprises a combustion chamber into which engine fuel is injected and in which it is burnt.

The heat-exchanger 104 may be designated, corresponding to its geometry for instance, as a plate heat-exchanger or, corresponding to the dual function for instance, as an oil-cooler insert.

FIG. 3 shows a third embodiment of the apparatus 100. The heat-exchanger 104 shown in the embodiment presented in FIG. 3 has been screwed in exemplary manner to a side wall of the oil sump 102, corresponding to the second embodiment. In a variant of the third embodiment, the heat-exchanger 104 is suspended in the oil sump 102, corresponding to the first embodiment presented in FIG. 1.

In the third embodiment, cooling water of an engine 130 which acts as a reservoir for the thermal medium serves as the thermal medium. Via a feeder 122 the cooling water is diverted from the cooling-water circuit of the engine 130 and heated in the external heat-source 106 to the forward-feed temperature in the forward feed 124 in accordance with the thermal power determined by the regulation system 120. For this purpose the heat-source 106 is connected to the connecting pipe 116 for the forward feed. The connecting pipe 118 for the return feed 126 is connected to a cooling-water reservoir of the engine 130. For the heating of the lubricating oil 108 in preparation for the cold start of the engine 130, the engine 130 serves as a reservoir for the thermal medium.

The regulation system 120 is connected to a first temperature sensor 121 which registers the oil temperature of the lubricating oil 108 in the oil sump 102. In a first implementation of the regulation system 120, the actual temperature of the lubricating oil 108 registered by means of the temperature sensor 121 determines the power output of the external heat-source 106.

Optionally, a second temperature sensor is arranged on the forward feed 124 for the purpose of registering the forward-feed temperature of the thermal medium. In a second implementation of the regulation system 120, a desired value for the forward-feed temperature in the forward feed 124 is determined on the basis of the actual temperature of the lubricating oil 108 registered by means of the first temperature sensor 121. The regulation system 120 regulates the power output of the external heat-source 106 on the basis of the difference between the desired value of the forward-feed temperature and the forward-feed temperature registered by the second sensor.

In the third embodiment shown in FIG. 3, a second temperature sensor 128 (as an alternative to or in supplement to the temperature sensor for the forward-feed temperature) is arranged in the return feed 126. In a third implementation of the regulation system 120, the regulation system 120 registers the return-feed temperature by means of the second temperature sensor 128 and regulates the power output of the external heat-source 106 in such a way that the return-feed temperature is higher than a minimal temperature of the lubricating oil 108 for the cold start. Furthermore, the regulation system 120 limits the power output of the external heat-source 106 if the return-feed temperature registered by means of the second sensor 128 exceeds a maximal temperature for the cooling water of the engine 130. By virtue of the regulation on the basis of the second sensor 128, the engine 130 can be employed as a reservoir for the thermal medium, without the engine 130 being exposed to too great a temperature gradient, since cooling water and lubricating oil are temperature-controlled by the same heat-source 106.

The circuit 122, 124 and 126 of the thermal medium is driven by a pump which is likewise controlled by the regulation system 120. The pump for the thermal medium is arranged in the feeder 122, for instance.

As an alternative to or in supplement to the cold start, the apparatus 100 can also be employed in operation of the engine 130 for the purpose of controlling the temperature both of the lubricating oil 108 and of the cooling water of the engine 130. In the course of operation as a heat-retaining apparatus, according to the third embodiment in FIG. 3 the supply of thermal medium is effected via the engine 130. The external heat-source 106 heats the cooling water as the thermal medium, which via the heat-exchanger 104 additionally keeps the lubricating oil 108 in the oil sump 102 warm. This can occur in unregulated manner or (as described above) in regulated manner. In the case of unregulated control of the external heat-source 106, the thermal medium is heated continuously or by a firmly predetermined pulse-rate of the thermal output. Alternatively, the pulse-rate may depend on the ambient temperature.

In the case of regulated operation of the external heat-source 106 in operation of the engine 130, the oil temperature and/or the temperature of the thermal medium (that is to say, of the cooling water) is/are monitored by the regulation system 120. The external heat-source 106 is switched on by the regulation system 120 if a defined temperature value is fallen below.

The apparatus 100 for heating lubricating oil for an internal-combustion engine, in particular the heating function and/or heat-retaining function thereof, can be employed in a vehicle (for instance, a utility vehicle) or in an engine 130 being operated when stationary. The utility vehicle may be, in particular, a military vehicle. The heat-retaining function can intervene, for instance, for the purpose of ensuring a minimum temperature of the lubricating oil 108 (and, where appropriate, of the cooling water) whenever the engine 130 is idling or is only loaded slightly.

FIG. 4 shows a fourth embodiment of the apparatus 100. Identical reference symbols label features described above. Departing from the third embodiment, in the fourth embodiment of the apparatus 100 a specific reservoir 130 for the thermal medium is provided. The reservoir 130 is preferentially arranged near the external heat-source. For instance, the external heat-source 106 is arranged in the reservoir 130. The circuit 124 and 126 of the thermal medium may be separate from a cooling-water circuit of the internal-combustion engine. A pump for conveying the thermal medium is arranged in the forward feed 14, for instance.

FIGS. 5 and 6 show perspective representations of an exemplary configuration of the second embodiment. The heat-exchanger 104 has been screwed to the oil sump 102 on a side wall 140 of the oil sump 102 by screws 138. The screws 138 are arranged diametrically with respect to the axis of the connecting pipes 116 and 118. The connecting pipes 116 and 118 lead into ports 134 and 136 outside the oil sump 102.

In the further development of the second embodiment shown in FIGS. 5 and 6 the ports 134 and 136 are each designed for a thread-free quick-acting closure. The quick-acting closure includes a peripheral groove at each port. For fluid-tight connection by means of the quick-acting closure, a sleeve is fastened to one end of a connecting hose. Within the sleeve a resilient latching element is arranged which engages with the peripheral groove whenever such a sleeve is pushed over, in each instance, one of the ports 134 and 136.

The oil sump 102 exhibits a peripheral mounting flange 132 with a plurality of peripherally arranged bores 133 which by virtue of, in each instance, an indentation in the oil sump 102 are accessible from outside the oil sump 102 for the purpose of mounting the oil sump 102. In the first embodiment, the thermal plates 114 are arranged in the oil sump 102 parallel to the plane of the peripheral flange 132. In the second embodiment, the thermal plates 114 are arranged perpendicular to the plane of the peripheral flange 132.

FIG. 7 shows a first example of an alternative arrangement which can also be put into effect in connection with each of the above embodiments. The parallel thermal plates 114 of the heat-exchanger 104 are arranged at an angle 142 relative to the plane of the connecting flange 132. The angle 142 may amount to between 0° and 180°, for instance 5°, 15°, 30°, 45°, 60°, 120°, 135°, 150°, 165° or 175°.

The suction point 110 may be in alignment with one of the thermal plates 114, so that the oil 108 flows through the interspaces between the thermal plates 114 immediately before it enters the suction point 110.

FIG. 8 shows a second example of an alternative arrangement which likewise can be put into effect in connection with each of the above embodiments. The side wall 140 of the oil sump bearing the heat-exchanger 104 is inclined, so that a horizontal cross section of the oil sump 102 tapers downwards. The parallel thermal plates 114 of the heat-exchanger 104 are arranged at an angle 142 relative to the plane of the connecting flange 132, so that the thermal plates 114 are parallel to the side wall 140.

The inclination of the side wall 140 may correspond to an extraction bevel for a manufacture of the oil sump 102 by casting. The side wall 140 and the parallel thermal plates 114 may be inclined by an angle between 0° and 5° relative to the vertical (corresponding to an angle 142 between 85° and 90°). For instance, the inclination may amount to 2° to 3° (corresponding to an angle 142 of 87° to 88°). The oil sump may be an aluminium casting.

As a result, oil 108 circulating in the oil sump 102 is able to flow through the interspaces between the thermal plates 114 by reason of the circulatory motion in the oil sump 102 for the effective exchange of heat with the thermal medium. In particular, a through-flow direction of the thermal medium (from the forward feed connecting pipe 116 to the return feed connecting pipe 118) in the heat-exchanger 104 may be opposite at the location of the heat-exchanger 104 to the direction of flow of the circulating oil 108. An oil pump can propel the circulation of the oil 108.

Although the present disclosure has been described with respect to exemplary embodiments, for a person skilled in the art it is evident that various changes may be made and equivalents may be used as substitutes. Furthermore, many modifications may be made in order to adapt a certain situation or a certain material to the teaching of the disclosure. Consequently the disclosure is not restricted to the disclosed embodiments but encompasses all embodiments that fall within the scope of the appended claims.

LIST OF REFERENCE SYMBOLS

-   100 apparatus for heating lubricating oil for an internal-combustion     engine -   102 oil sump -   104 heat-exchanger -   106 heat-source -   108 lubricating oil -   110 suction point -   112 desired level -   114 thermal plate -   116 connecting pipe for forward feed -   118 connecting pipe for return feed -   120 regulation system -   121 first temperature sensor -   122 feeder -   124 forward feed -   126 return feed -   128 second temperature sensor -   130 engine or reservoir -   132 connecting flange -   133 bore in the connecting flange -   134 port for forward feed -   136 port for return feed -   138 screw joint of the heat-exchanger -   140 side wall of the oil sump -   142 angle between thermal plates and flange face 

We claim:
 1. An apparatus for heating lubricating oil for an internal-combustion engine, comprising: a heat-exchanger arranged within an oil sump of the internal-combustion engine, which is flowed through or capable of being flowed through by a thermal medium for the purpose of emitting heat to lubricating oil in the oil sump; and a heat-source in fluidic communication with the heat-exchanger, which is designed to heat the thermal medium outside the oil sump and outside the internal-combustion engine.
 2. The apparatus according to claim 1, further comprising at least one sensor for registering at least one temperature.
 3. The apparatus according to claim 1, further comprising a sensor for registering an actual temperature of the lubricating oil in the oil sump, a sensor for registering a forward-feed temperature in a forward feed of the heat-exchanger, or a sensor for registering the return-feed temperature in a return feed of the heat-exchanger.
 4. The apparatus according to claim 2, further comprising a regulation system which is designed to regulate a power output of the heat-source in a manner depending on the at least one registered temperature.
 5. The apparatus according to claim 3, wherein the power output of the heat-source is regulated in such a way that the registered forward-feed temperature or the registered return-feed temperature of the heat-exchanger is higher than the actual temperature or a desired temperature of the lubricating oil in the oil sump.
 6. The apparatus according to claim 1, further comprising a reservoir of the thermal medium, arranged outside the oil sump, the heat-exchanger and the reservoir being in fluidic communication in a circuit of the thermal medium.
 7. The apparatus according to claim 5, wherein the return-feed temperature is registered between the heat-exchanger and the reservoir of the thermal medium.
 8. The apparatus according to claim 7, wherein the regulation system is further designed to reduce the power output of the heat-source if the return-feed temperature is higher than a predetermined maximal temperature of the reservoir.
 9. The apparatus according to claim 1, further comprising a suction point of a lubricating-oil circuit spatially assigned to the heat-exchanger is arranged in the oil sump.
 10. The apparatus according to claim 1, wherein the heat-exchanger includes a plurality of heat-conducting plates arranged in parallel, with cavities in which the thermal medium flows.
 11. The apparatus according to claim 10, wherein the plates are spaced from one another for the purpose of forming interspaces between the plates, into which the lubricating oil flows.
 12. The apparatus according to claim 10, wherein the oil sump includes a peripheral connecting flange and the plates are arranged parallel to a plane of the connecting flange, and wherein the heat-exchanger includes connecting pipes and which are arranged within the peripheral connecting flange.
 13. The apparatus according to claim 10, wherein the oil sump includes a peripheral connecting flange and the plates are arranged perpendicular to a plane of the connecting flange, and wherein the heat-exchanger includes connecting pipes and which lead through a side wall of the oil sump and are screwed to the side wall.
 14. The apparatus according to claim 10, wherein the oil sump includes a peripheral connecting flange and the plates are arranged at an angle, different from 0° or 90°, relative to the plane of the connecting flange.
 15. The apparatus according to claim 1, wherein the thermal medium comprises cooling water of the internal-combustion engine. 